1. Field of Invention
The invention relates to a tap water purifier to be directly coupled to a faucet pipe for purifying tap water from the faucet pipe.
2. Description of the Prior Art
A tap water purifier to be directly coupled to a faucet pipe has been commonly used, which comprises a water purifying barrel filled with a filter medium such as active carbon, ceramics or hollow yarn. The purifying barrel is received in a receptacle which is fixedly connected to a changeover cock. The changeover cock is attached to the opening end of a faucet pipe so that the tap water flows from the faucet pipe into the purifying barrel in the receptacle through the changeover cock. The tap water is purified by the filter medium in the purifying barrel and then discharged from the lower end of the receptacle. The changeover cock includes a lever which can be turned through a given angle to switch the flow path in the changeover cock so that the tap water is discharged from the lower end of the changeover cock without passing through the receptacle and the purifying barrel. The purifying barrel is cartridge type which can be removed from the receptacle for exchange for a fresh one when the water purifier has been used for a long time and the purifying effect thereof is lowered.
The tap water purifier has a problem that the purifying barrel is subject to internal contamination with the dirt, iron rust or algae contained in the tap water as it is used. The contamination causes a hotbed of germs. The contamination also results in the clogging of the filter medium. Therefore, it is desirable to periodically clean the purifying barrel in the receptacle to eliminate the contamination before it is exchanged for a fresh one. However, it is virtually difficult to periodically clean the purifying barrel in the receptacle. In addition, the tap water purifier has another problem that water channels are formed in the filter medium as it is used so that the tap water flows through the water channels without being purified effectively.
Further, it is known that chlorine is contained in the tap water from the faucet pipe, the chlorine having a sterilizing effect. It is also known that the chlorine is removed from the tap water by the filter medium in the tap water purifier so that no chlorine is contained in the purified water discharged from the lower end of the receptacle. When the faucet of the faucet pipe is closed to stop the tap water, the purified water devoid of chlorine is stagnant between the purifying barrel in the receptacle and the lower end of the receptacle. Accordingly, in the case where the tap water purifier is left unused for a long time, various germs adhere to the lower end of the receptacle and breed in the purified water to enter the purifying barrel and breed therein.